The purpose is to complete the evaluation of a newly developed trileaflet prosthetic aortic valve and to initiate developmental studies and innovative fabrication techniques for production of mitral and tricuspid leaflet prosthetic valves. Additionally, the technology gained will be used to investigate the feasibility of small diameter arterial prostheses. The principles previously developed of anisotropic properties, composite material technology together with the concepts of both morphological and chemical importance of surfaces will be used. Stress distribution analyses using stereophotogrammetry, finite element computational techniques and optimization analyses will be performed. Fabrication techniques using ultra-pure polyester, springy polypropylene, microweaving and microcrimping methods previously developed will be used. Increased emphases to testing methodology will be given. Strong interaction with the Blood Degradation Project using the spinning disc apparatus to ascertain red cell and platelet adhesion as a function of shear and contact angle studies will be performed. Increased activity in the critical hydrodynamic and fatigue testing areas reflects the shifting emphases to quantitative in vitro evaluation as many of the anatomic based design problems have progressed. Flow field and streaming birefringence studies and high order precise instrumentation of accelerated fatigue systems will be further refined. Biologic evaluations will continue on the micro-scaffold, microfiber surfaces that contain proven anti-bacterial properties and high heparin activity. Animal testing will continue with the descending aorta dog model and valve replacement in baboons will be initiated. BIBLIOGRAPHIC REFERENCES: Cataloglu, A., Clark, R. E., and Gould, P. L. Aortic Valve Leaflets with Smooth Geometrical Data, J. Applied Mechanics, Div. ASME, 1976, in press. Grogan, E. L., Sande, M. A., Clark, R. E., Schneider, J. E., and Nolan, S. P. Production and Course of Experimental Prosthetic Valve Endocarditis, Circulation, 1976, in press.